1. Field of the Invention
The present application relates to polyarylenesulfide resin compositions having a dramatically improved adhesiveness with regard to a cured epoxy resin, while retaining characteristic properties of polyarylenesulfide resins such as heat resistance and chemical resistance; and relates practically to useful polyarylenesulfide resin compositions in a wide range of industrial fields, such as an ignition coil case for cars used by sealing the ignition coil in the coil case made of the polyarylenesulfide resin with an epoxy resin composition; and a coil case in a so-called “distributorless ignition system (hereinafter, abbreviated as “DLI”) which is produced by integrating the plug and an ignition coil; and furthermore relates to electric and electronic components such as epoxy resin sealed type semiconductor devices.
2. Background Art
Recently, polyarylenesulfide (hereinafter, abbreviated as “PAS”) has attracted attention as an excellent engineering plastic having superior heat and chemical resistances.
One of the application fields of the PAS resin utilizing these features is producing various electronic and electric components by sealing various electronic electric elements in casings made of the PAS resin composition formed in advance by injection molding. That is, in order to develop a new technique for producing electronic and electric components (especially, ignition coils for DLI), semiconductor elements or coils are first mounted in a casing made of PAS resin, uncured epoxy resin is poured in the casing for sealing these elements or coils, and the epoxy resin is finally cured by, for example, heat treatment for sealing these semiconductor elements or coils into the casing.
When the PAS resin is used for such applications, it is necessary for the PAS resin products to be provided with a superior long-term adhesiveness to the epoxy resin at wide ranges of usage temperatures, in addition to the intrinsic characteristics such as long-term heat and chemical resistance properties. Practically, it is required that the PAS resin products sealed by epoxy resin do not peel off from the epoxy sealant, even when the PAS resin products sealed by epoxy resin is repeatedly used in a temperature range of −40° C. to 140° C. As a matter of fact, since the PAS resin is intrinsically inferior in adhesiveness to epoxy resin, and the adhesion is weak even if it is reinforced by glass fibers or the like, the PAS resin has been considered not suitable for use for sealing applications with epoxy resins.
In order to improve the adhesion of the PAS resin with the epoxy resin, Japanese Patent Application, First Publication No. Hei 9-3326, discloses a technique for improving the adhesion by addition of α-olefine/α,β-unsaturated carboxylic acid glycidylester copolymer and an amide carboxylic acid-type wax to the PAS resin for relieving stress caused at an interface between the PAS resin and the epoxy resin at the time of heating and cooling.
However, the PAS resin composition disclosed in Japanese Patent Application, First Publication No. Hei 9-3326, does not exhibit a satisfactory adhesiveness with the epoxy resin and generation of cracks are observed in the heating and cooling cycles, which means that conventional PAS resins are not sufficient to satisfy the level for practical use.